Question

Which of the following atom has the largest second ionization energy?

• A. Silicon, $Si$
• B. Calcium, $Ca$
• C. Chlorine, $Cl$
• D. Iron,$Fe$
• E. Sodium,$Na$

Answer 1

Answer: (E)

Sodium,$Na$

Sodium atoms have the largest second ionization energy.
When sodium loses one electron, it forms $N{a}^{+}$ ion which has stable electronic configuration of the noble gas $Ne$.
When $N{a}^{+}$ ions loses an electron, this stable configuration of $Ne$ is broken. This requires high amount of energy. Hence, second ionization energy of sodium is largest.